lp2hp — SciPy v1.15.3 Manual (original) (raw)

scipy.signal.

scipy.signal.lp2hp(b, a, wo=1.0)[source]#

Transform a lowpass filter prototype to a highpass filter.

Return an analog high-pass filter with cutoff frequency _wo_from an analog low-pass filter prototype with unity cutoff frequency, in transfer function (‘ba’) representation.

Parameters:

barray_like

Numerator polynomial coefficients.

aarray_like

Denominator polynomial coefficients.

wofloat

Desired cutoff, as angular frequency (e.g., rad/s). Defaults to no change.

Returns:

barray_like

Numerator polynomial coefficients of the transformed high-pass filter.

aarray_like

Denominator polynomial coefficients of the transformed high-pass filter.

Notes

This is derived from the s-plane substitution

\[s \rightarrow \frac{\omega_0}{s}\]

This maintains symmetry of the lowpass and highpass responses on a logarithmic scale.

Examples

from scipy import signal import matplotlib.pyplot as plt

lp = signal.lti([1.0], [1.0, 1.0]) hp = signal.lti(*signal.lp2hp(lp.num, lp.den)) w, mag_lp, p_lp = lp.bode() w, mag_hp, p_hp = hp.bode(w)

plt.plot(w, mag_lp, label='Lowpass') plt.plot(w, mag_hp, label='Highpass') plt.semilogx() plt.grid(True) plt.xlabel('Frequency [rad/s]') plt.ylabel('Amplitude [dB]') plt.legend()